Targeted expression of L-myo- inositol 1-phosphate synthase from Porteresia coarctata (Roxb.) Tateoka confers multiple stress tolerance in transgenic crop plants

Improving crop tolerance to osmotic stresses is a longstanding goal of agricultural biotechnology. In the present work the PcINO1 gene coding for a salt-tolerant L-myo-inositol-1-phosphate synthase (MIPS) from Porteresia coarctata (Roxb.) Tateoka, a halophytic wild rice was introgressed into cultivated mustard, Brassica juncea var B85. The transgenic plants demonstrate increased tolerance to salinity and oxidative stress with elevated level of inositol in both roots and shoots. The yield and crop quality of transgenic Brassica plants remain uncompromised and the plants were able to stably grow, set seeds and germinate in saline environments. When targeted to seeds of Nicotiana, PcINO1 was able to improve the seed survival rate under salinity and dehydration. Inositol and its derivatives regulate stress responses in various ways, serving as compatible solutes or signaling molecules. It is implicated that engineering inositol metabolism may affect the plant metabolic network leading to a stress tolerant phenotype as enumerated here in transgenic crop plants. How inositol itself or its derivatives affect the overall metabolic pathways leading to a stress-tolerant phenotype remains an intriguing question for future investigations.